CKinect.cpp

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/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file        |
   | See: http://www.mrpt.org/Authors - All rights reserved.                   |
   | Released under BSD License. See details in http://www.mrpt.org/License    |
   +---------------------------------------------------------------------------+ */

#include "hwdrivers-precomp.h"   // Precompiled headers

#include <mrpt/hwdrivers/CKinect.h>
#include <mrpt/utils/CTimeLogger.h>
#include <mrpt/utils/TStereoCamera.h>

// Universal include for all versions of OpenCV
#include <mrpt/otherlibs/do_opencv_includes.h>

using namespace mrpt::hwdrivers;
using namespace mrpt::system;
using namespace mrpt::synch;
using namespace mrpt::utils;
using namespace mrpt::math;
using namespace mrpt::obs;
using namespace mrpt::poses;
using namespace std;

IMPLEMENTS_GENERIC_SENSOR(CKinect,mrpt::hwdrivers)

// Whether to profile memory allocations:
//#define KINECT_PROFILE_MEM_ALLOC

#if MRPT_HAS_KINECT_FREENECT
# if defined(__APPLE__)
#  include <libfreenect/libfreenect.h>
# else
#  include <libfreenect.h>
#endif
#else
#       define KINECT_W 640
#       define KINECT_H 480
#endif

#if MRPT_HAS_KINECT_FREENECT
        // Macros to convert the opaque pointers in the class header:
        #define f_ctx  reinterpret_cast<freenect_context*>(m_f_ctx)
        #define f_ctx_ptr  reinterpret_cast<freenect_context**>(&m_f_ctx)
        #define f_dev  reinterpret_cast<freenect_device*>(m_f_dev)
        #define f_dev_ptr  reinterpret_cast<freenect_device**>(&m_f_dev)
#endif // MRPT_HAS_KINECT_FREENECT


#ifdef KINECT_PROFILE_MEM_ALLOC
mrpt::utils::CTimeLogger alloc_tim;
#endif
//int int a;

void CKinect::calculate_range2meters()
{
#ifdef MRPT_KINECT_DEPTH_10BIT
        const float k1 = 1.1863f;
        const float k2 = 2842.5f;
        const float k3 = 0.1236f;

        for (size_t i=0; i<KINECT_RANGES_TABLE_LEN; i++)
                        m_range2meters[i] = k3 * tanf(i/k2 + k1);

#else
        for (size_t i=0; i<KINECT_RANGES_TABLE_LEN; i++)
                m_range2meters[i] = 1.0f / (i * (-0.0030711016) + 3.3309495161);
#endif

        // Minimum/Maximum range means error:
        m_range2meters[0] = 0;
        m_range2meters[KINECT_RANGES_TABLE_LEN-1] = 0;
}

/*-------------------------------------------------------------
                ctor
 -------------------------------------------------------------*/
CKinect::CKinect()  :
        m_sensorPoseOnRobot(),
        m_preview_window(false),
        m_preview_window_decimation(1),
        m_preview_decim_counter_range(0),
        m_preview_decim_counter_rgb(0),

#if MRPT_HAS_KINECT_FREENECT
        m_f_ctx(NULL), // The "freenect_context", or NULL if closed
        m_f_dev(NULL), // The "freenect_device", or NULL if closed
        m_tim_latest_depth(0),
        m_tim_latest_rgb(0),
        m_latest_obs_cs("m_latest_obs_cs"),
#endif
        m_relativePoseIntensityWRTDepth(0,-0.02,0, DEG2RAD(-90),DEG2RAD(0),DEG2RAD(-90)),
        m_initial_tilt_angle(360),
        m_user_device_number(0),
        m_grab_image(true),
        m_grab_depth(true),
        m_grab_3D_points(true),
        m_grab_IMU(true),
        m_video_channel(VIDEO_CHANNEL_RGB)
{
        calculate_range2meters();

        // Get maximum range:
        m_maxRange=m_range2meters[KINECT_RANGES_TABLE_LEN-2];  // Recall: r[Max-1] means error.

        // Default label:
        m_sensorLabel = "KINECT";

        // =========== Default params ===========
        // ----- RGB -----
        m_cameraParamsRGB.ncols = 640; // By default set 640x480, on connect we'll update this.
        m_cameraParamsRGB.nrows = 480;

        m_cameraParamsRGB.cx(328.94272028759258);
        m_cameraParamsRGB.cy(267.48068171871557);
        m_cameraParamsRGB.fx(529.2151);
        m_cameraParamsRGB.fy(525.5639);

        m_cameraParamsRGB.dist.zeros();

        // ----- Depth -----
        m_cameraParamsDepth.ncols = 640;
        m_cameraParamsDepth.nrows = 488;

        m_cameraParamsDepth.cx(339.30781);
        m_cameraParamsDepth.cy(242.7391);
        m_cameraParamsDepth.fx(594.21434);
        m_cameraParamsDepth.fy(591.04054);

        m_cameraParamsDepth.dist.zeros();

#if !MRPT_HAS_KINECT
        THROW_EXCEPTION("MRPT was compiled without support for Kinect. Please, rebuild it.")
#endif
}

/*-------------------------------------------------------------
                        dtor
 -------------------------------------------------------------*/
CKinect::~CKinect()
{
        this->close();
}

/** This method can or cannot be implemented in the derived class, depending on the need for it.
*  \exception This method must throw an exception with a descriptive message if some critical error is found.
*/
void CKinect::initialize()
{
        open();
}

/** This method will be invoked at a minimum rate of "process_rate" (Hz)
*  \exception This method must throw an exception with a descriptive message if some critical error is found.
*/
void CKinect::doProcess()
{
        bool    thereIs, hwError;

        CObservation3DRangeScanPtr newObs     = CObservation3DRangeScan::Create();
        CObservationIMUPtr         newObs_imu = CObservationIMU::Create();

        getNextObservation( *newObs, *newObs_imu, thereIs, hwError );

        if (hwError)
        {
                m_state = ssError;
            THROW_EXCEPTION("Couldn't communicate to the Kinect sensor!");
        }

        if (thereIs)
        {
                m_state = ssWorking;

                vector<CSerializablePtr> objs;
                if (m_grab_image || m_grab_depth || m_grab_3D_points)  objs.push_back(newObs);
                if (m_grab_IMU)  objs.push_back(newObs_imu);

                appendObservations( objs );
        }
}

/** Loads specific configuration for the device from a given source of configuration parameters, for example, an ".ini" file, loading from the section "[iniSection]" (see utils::CConfigFileBase and derived classes)
*  \exception This method must throw an exception with a descriptive message if some critical parameter is missing or has an invalid value.
*/
void  CKinect::loadConfig_sensorSpecific(
        const mrpt::utils::CConfigFileBase &configSource,
        const std::string                       &iniSection )
{
        m_sensorPoseOnRobot.setFromValues(
                configSource.read_float(iniSection,"pose_x",0),
                configSource.read_float(iniSection,"pose_y",0),
                configSource.read_float(iniSection,"pose_z",0),
                DEG2RAD( configSource.read_float(iniSection,"pose_yaw",0) ),
                DEG2RAD( configSource.read_float(iniSection,"pose_pitch",0) ),
                DEG2RAD( configSource.read_float(iniSection,"pose_roll",0) )
                );

        m_preview_window = configSource.read_bool(iniSection,"preview_window",m_preview_window);

        // "Stereo" calibration data:
        // [<SECTION>_LEFT]  // Depth
        //   ...
        // [<SECTION>_RIGHT] // RGB
        //   ...
        // [<SECTION>_LEFT2RIGHT_POSE]
        //  pose_quaternion = [x y z qr qx qy qz]

        const mrpt::poses::CPose3D twist(0,0,0,DEG2RAD(-90),DEG2RAD(0),DEG2RAD(-90));

        mrpt::utils::TStereoCamera  sc;
        sc.leftCamera  = m_cameraParamsDepth;  // Load default values so that if we fail to load from cfg at least we have some reasonable numbers.
        sc.rightCamera = m_cameraParamsRGB;
        sc.rightCameraPose = mrpt::poses::CPose3DQuat(m_relativePoseIntensityWRTDepth - twist);

        try {
                sc.loadFromConfigFile(iniSection,configSource);
        } catch (std::exception &e) {
                std::cout << "[CKinect::loadConfig_sensorSpecific] Warning: Ignoring error loading calibration parameters:\n" << e.what();
        }
        m_cameraParamsDepth = sc.leftCamera;
        m_cameraParamsRGB   = sc.rightCamera;
        m_relativePoseIntensityWRTDepth = twist + mrpt::poses::CPose3D(sc.rightCameraPose);

        // Id:
        m_user_device_number = configSource.read_int(iniSection,"device_number",m_user_device_number );

        m_grab_image = configSource.read_bool(iniSection,"grab_image",m_grab_image);
        m_grab_depth = configSource.read_bool(iniSection,"grab_depth",m_grab_depth);
        m_grab_3D_points = configSource.read_bool(iniSection,"grab_3D_points",m_grab_3D_points);
        m_grab_IMU = configSource.read_bool(iniSection,"grab_IMU",m_grab_IMU );

        m_video_channel = configSource.read_enum<TVideoChannel>(iniSection,"video_channel",m_video_channel);

        {
                std::string s = configSource.read_string(iniSection,"relativePoseIntensityWRTDepth","");
                if (!s.empty())
                        m_relativePoseIntensityWRTDepth.fromString(s);
        }

        m_initial_tilt_angle = configSource.read_int(iniSection,"initial_tilt_angle",m_initial_tilt_angle);
}

bool CKinect::isOpen() const
{
#if MRPT_HAS_KINECT_FREENECT
        return f_dev != NULL;
#else
        return false;
#endif

#
}


#if MRPT_HAS_KINECT_FREENECT
// ========  GLOBAL CALLBACK FUNCTIONS ========
void depth_cb(freenect_device *dev, void *v_depth, uint32_t timestamp)
{
        const freenect_frame_mode frMode = freenect_get_current_video_mode(dev);

        uint16_t *depth = reinterpret_cast<uint16_t *>(v_depth);

        CKinect *obj = reinterpret_cast<CKinect*>(freenect_get_user(dev));

        // Update of the timestamps at the end:
        mrpt::synch::CCriticalSectionLocker lock( &obj->internal_latest_obs_cs() );
        CObservation3DRangeScan &obs = obj->internal_latest_obs();

        obs.hasRangeImage  = true;
        obs.range_is_depth = true;

#ifdef KINECT_PROFILE_MEM_ALLOC
        alloc_tim.enter("depth_cb alloc");
#endif

        // This method will try to exploit memory pooling if possible:
        obs.rangeImage_setSize(frMode.height,frMode.width);

#ifdef KINECT_PROFILE_MEM_ALLOC
        alloc_tim.leave("depth_cb alloc");
#endif

        const CKinect::TDepth2RangeArray &r2m = obj->getRawDepth2RangeConversion();
        for (int r=0;r<frMode.height;r++)
                for (int c=0;c<frMode.width;c++)
                {
                        // For now, quickly save the depth as it comes from the sensor, it'll
                        //  transformed later on in getNextObservation()
                        const uint16_t v = *depth++;
                        obs.rangeImage.coeffRef(r,c) = r2m[v & KINECT_RANGES_TABLE_MASK];
                }
        obj->internal_tim_latest_depth() = timestamp;
}

void rgb_cb(freenect_device *dev, void *img_data, uint32_t timestamp)
{
        CKinect *obj = reinterpret_cast<CKinect*>(freenect_get_user(dev));
        const freenect_frame_mode frMode = freenect_get_current_video_mode(dev);

        // Update of the timestamps at the end:
        mrpt::synch::CCriticalSectionLocker lock( &obj->internal_latest_obs_cs() );
        CObservation3DRangeScan &obs = obj->internal_latest_obs();

#ifdef KINECT_PROFILE_MEM_ALLOC
        alloc_tim.enter("depth_rgb loadFromMemoryBuffer");
#endif

        obs.hasIntensityImage = true;
        if (obj->getVideoChannel()==CKinect::VIDEO_CHANNEL_RGB)
        {
             // Color image: We asked for Bayer data, so we can decode it outselves here
             //  and avoid having to reorder Green<->Red channels, as would be needed with
             //  the RGB image from freenect.
          obs.intensityImageChannel = mrpt::obs::CObservation3DRangeScan::CH_VISIBLE;
          obs.intensityImage.resize(frMode.width, frMode.height, CH_RGB, true /* origin=top-left */ );

#if MRPT_HAS_OPENCV
#       if MRPT_OPENCV_VERSION_NUM<0x200
                  // Version for VERY OLD OpenCV versions:
                  IplImage *src_img_bayer = cvCreateImageHeader(cvSize(frMode.width,frMode.height),8,1);
                  src_img_bayer->imageDataOrigin = reinterpret_cast<char*>(img_data);
                  src_img_bayer->imageData = src_img_bayer->imageDataOrigin;
                  src_img_bayer->widthStep = frMode.width;

                  IplImage *dst_img_RGB = obs.intensityImage.getAs<IplImage>();

          // Decode Bayer image:
                  cvCvtColor(src_img_bayer, dst_img_RGB, CV_BayerGB2BGR);

#       else
                  // Version for modern OpenCV:
          const cv::Mat  src_img_bayer( frMode.height, frMode.width, CV_8UC1, img_data, frMode.width );

          cv::Mat        dst_img_RGB= cv::cvarrToMat( obs.intensityImage.getAs<IplImage>(), false /* dont copy buffers */ );

          // Decode Bayer image:
          cv::cvtColor(src_img_bayer, dst_img_RGB, CV_BayerGB2BGR);
#       endif
#else
     THROW_EXCEPTION("Need building with OpenCV!")
#endif

        }
        else
        {
             // IR data: grayscale 8bit
          obs.intensityImageChannel = mrpt::obs::CObservation3DRangeScan::CH_IR;
          obs.intensityImage.loadFromMemoryBuffer(
               frMode.width,
               frMode.height,
               false, // Color image?
               reinterpret_cast<unsigned char*>(img_data)
               );

        }

        //obs.intensityImage.setChannelsOrder_RGB();

#ifdef KINECT_PROFILE_MEM_ALLOC
        alloc_tim.leave("depth_rgb loadFromMemoryBuffer");
#endif

        obj->internal_tim_latest_rgb() = timestamp;
}
// ========  END OF GLOBAL CALLBACK FUNCTIONS ========
#endif // MRPT_HAS_KINECT_FREENECT


void CKinect::open()
{
        if (isOpen())
                close();

        // Alloc memory, if this is the first time:
        m_buf_depth.resize(640*480*3); // We'll resize this below if needed
        m_buf_rgb.resize(640*480*3);

#if MRPT_HAS_KINECT_FREENECT  // ----> libfreenect
        // Try to open the device:
        if (freenect_init(f_ctx_ptr, NULL) < 0)
                THROW_EXCEPTION("freenect_init() failed")

        freenect_set_log_level(f_ctx,
#ifdef _DEBUG
                FREENECT_LOG_DEBUG
#else
                FREENECT_LOG_WARNING
#endif
                );

        int nr_devices = freenect_num_devices(f_ctx);
        //printf("[CKinect] Number of devices found: %d\n", nr_devices);

        if (!nr_devices)
                THROW_EXCEPTION("No Kinect devices found.")

        // Open the given device number:
        if (freenect_open_device(f_ctx, f_dev_ptr, m_user_device_number) < 0)
                THROW_EXCEPTION_FMT("Error opening Kinect sensor with index: %d",m_user_device_number)

        // Setup:
        if (m_initial_tilt_angle!=360) // 360 means no motor command.
          setTiltAngleDegrees(m_initial_tilt_angle);
        freenect_set_led(f_dev,LED_RED);
        freenect_set_depth_callback(f_dev, depth_cb);
        freenect_set_video_callback(f_dev, rgb_cb);

        // rgb or IR channel:
        const freenect_frame_mode desiredFrMode = freenect_find_video_mode(
                FREENECT_RESOLUTION_MEDIUM,
                m_video_channel==VIDEO_CHANNEL_IR ?
                        FREENECT_VIDEO_IR_8BIT
                        :
                        FREENECT_VIDEO_BAYER // FREENECT_VIDEO_RGB: Use Bayer instead so we can directly decode it here
                );

        // Switch to that video mode:
        if (freenect_set_video_mode(f_dev, desiredFrMode)<0)
                THROW_EXCEPTION("Error setting Kinect video mode.")


        // Get video mode:
        const freenect_frame_mode frMode = freenect_get_current_video_mode(f_dev);

        // Realloc mem:
        m_buf_depth.resize(frMode.width*frMode.height*3);
        m_buf_rgb.resize(frMode.width*frMode.height*3);

        // Save resolution:
        m_cameraParamsRGB.ncols = frMode.width;
        m_cameraParamsRGB.nrows = frMode.height;

        m_cameraParamsDepth.ncols = frMode.width;
        m_cameraParamsDepth.nrows = frMode.height;

        freenect_set_video_buffer(f_dev, &m_buf_rgb[0]);
        freenect_set_depth_buffer(f_dev, &m_buf_depth[0]);

        freenect_set_depth_mode(f_dev, freenect_find_depth_mode(FREENECT_RESOLUTION_MEDIUM, FREENECT_DEPTH_10BIT));

        // Set user data = pointer to "this":
        freenect_set_user(f_dev, this);

        if (freenect_start_depth(f_dev)<0)
                THROW_EXCEPTION("Error starting depth streaming.")

        if (freenect_start_video(f_dev)<0)
                THROW_EXCEPTION("Error starting video streaming.")

#endif // MRPT_HAS_KINECT_FREENECT
}

void CKinect::close()
{
#if MRPT_HAS_KINECT_FREENECT
        if (f_dev)
        {
                freenect_stop_depth(f_dev);
                freenect_stop_video(f_dev);
                freenect_close_device(f_dev);
        }
        m_f_dev = NULL;

        if (f_ctx)
                freenect_shutdown(f_ctx);
        m_f_ctx = NULL;
#endif // MRPT_HAS_KINECT_FREENECT
}

/** Changes the video channel to open (RGB or IR) - you can call this method before start grabbing or in the middle of streaming and the video source will change on the fly.
        Default is RGB channel.
*/
void  CKinect::setVideoChannel(const TVideoChannel vch)
{
#if MRPT_HAS_KINECT_FREENECT
        m_video_channel = vch;
        if (!isOpen()) return; // Nothing else to do here.

        // rgb or IR channel:
        freenect_stop_video(f_dev);

        // rgb or IR channel:
        const freenect_frame_mode desiredFrMode = freenect_find_video_mode(
                FREENECT_RESOLUTION_MEDIUM,
                m_video_channel==VIDEO_CHANNEL_IR ?
                        FREENECT_VIDEO_IR_8BIT
                        :
                        FREENECT_VIDEO_BAYER // FREENECT_VIDEO_RGB: Use Bayer instead so we can directly decode it here
                );

        // Switch to that video mode:
        if (freenect_set_video_mode(f_dev, desiredFrMode)<0)
                THROW_EXCEPTION("Error setting Kinect video mode.")

        freenect_start_video(f_dev);

#else
        MRPT_UNUSED_PARAM(vch);
#endif // MRPT_HAS_KINECT_FREENECT
}


/** The main data retrieving function, to be called after calling loadConfig() and initialize().
  *  \param out_obs The output retrieved observation (only if there_is_obs=true).
  *  \param there_is_obs If set to false, there was no new observation.
  *  \param hardware_error True on hardware/comms error.
  *
  * \sa doProcess
  */
void CKinect::getNextObservation(
        mrpt::obs::CObservation3DRangeScan &_out_obs,
        bool &there_is_obs,
        bool &hardware_error )
{
        there_is_obs=false;
        hardware_error = false;

#if MRPT_HAS_KINECT_FREENECT

        static const double max_wait_seconds = 1./25.;
        static const TTimeStamp max_wait = mrpt::system::secondsToTimestamp(max_wait_seconds);

        // Mark previous observation's timestamp as out-dated:
        m_latest_obs.hasPoints3D        = false;
        m_latest_obs.hasRangeImage      = false;
        m_latest_obs.hasIntensityImage  = false;
        m_latest_obs.hasConfidenceImage = false;

        const TTimeStamp tim0 = mrpt::system::now();

        // Reset these timestamp flags so if they are !=0 in the next call we're sure they're new frames.
        m_latest_obs_cs.enter();
        m_tim_latest_rgb   = 0;
        m_tim_latest_depth = 0;
        m_latest_obs_cs.leave();

        while (freenect_process_events(f_ctx)>=0 && mrpt::system::now()<(tim0+max_wait) )
        {
                // Got a new frame?
                if ( (!m_grab_image || m_tim_latest_rgb!=0) &&   // If we are NOT grabbing RGB or we are and there's a new frame...
                         (!m_grab_depth || m_tim_latest_depth!=0)    // If we are NOT grabbing Depth or we are and there's a new frame...
                   )
                {
                        // Approx: 0.5ms delay between depth frame (first) and RGB frame (second).
                        //cout << "m_tim_latest_rgb: " << m_tim_latest_rgb << " m_tim_latest_depth: "<< m_tim_latest_depth <<endl;
                        there_is_obs=true;
                        break;
                }
        }

        // Handle the case when there is NOT depth frames (if there's something very close blocking the IR sensor) but we have RGB:
        if ( (m_grab_image && m_tim_latest_rgb!=0) &&
                 (m_grab_depth && m_tim_latest_depth==0) )
        {
                // Mark the entire range data as invalid:
                m_latest_obs.hasRangeImage = true;
                m_latest_obs.range_is_depth = true;

                m_latest_obs_cs.enter(); // Important: if system is running slow, etc. we cannot tell for sure that the depth buffer is not beeing filled right now:
                m_latest_obs.rangeImage.setSize(m_cameraParamsDepth.nrows,m_cameraParamsDepth.ncols);
                m_latest_obs.rangeImage.setConstant(0); // "0" means: error in range
                m_latest_obs_cs.leave();
                there_is_obs=true;
        }


        if (!there_is_obs)
                return;


        // We DO have a fresh new observation:

        // Quick save the observation to the user's object:
        m_latest_obs_cs.enter();
                _out_obs.swap(m_latest_obs);
        m_latest_obs_cs.leave();
#endif

        // Set common data into observation:
        // --------------------------------------
        _out_obs.sensorLabel = m_sensorLabel;
        _out_obs.timestamp = mrpt::system::now();
        _out_obs.sensorPose = m_sensorPoseOnRobot;
        _out_obs.relativePoseIntensityWRTDepth = m_relativePoseIntensityWRTDepth;

        _out_obs.cameraParams          = m_cameraParamsDepth;
        _out_obs.cameraParamsIntensity = m_cameraParamsRGB;

        // 3D point cloud:
        if ( _out_obs.hasRangeImage && m_grab_3D_points )
        {
                _out_obs.project3DPointsFromDepthImage();

                if ( !m_grab_depth )
                {
                        _out_obs.hasRangeImage = false;
                        _out_obs.rangeImage.resize(0,0);
                }

        }

        // preview in real-time?
        if (m_preview_window)
        {
                if ( _out_obs.hasRangeImage )
                {
                        if (++m_preview_decim_counter_range>m_preview_window_decimation)
                        {
                                m_preview_decim_counter_range=0;
                                if (!m_win_range)       { m_win_range = mrpt::gui::CDisplayWindow::Create("Preview RANGE"); m_win_range->setPos(5,5); }

                                // Normalize the image
                                mrpt::utils::CImage  img;
                                img.setFromMatrix(_out_obs.rangeImage);
                                CMatrixFloat r = _out_obs.rangeImage * float(1.0/this->m_maxRange);
                                m_win_range->showImage(img);
                        }
                }
                if ( _out_obs.hasIntensityImage )
                {
                        if (++m_preview_decim_counter_rgb>m_preview_window_decimation)
                        {
                                m_preview_decim_counter_rgb=0;
                                if (!m_win_int)         { m_win_int = mrpt::gui::CDisplayWindow::Create("Preview INTENSITY"); m_win_int->setPos(300,5); }
                                m_win_int->showImage(_out_obs.intensityImage );
                        }
                }
        }
        else
        {
                if (m_win_range) m_win_range.clear();
                if (m_win_int) m_win_int.clear();
        }
}

/* -----------------------------------------------------
                                getNextObservation (with IMU)
----------------------------------------------------- */
void CKinect::getNextObservation(
        mrpt::obs::CObservation3DRangeScan &out_obs,
        mrpt::obs::CObservationIMU         &out_obs_imu,
        bool &there_is_obs,
        bool &hardware_error )
{
        // First, try getting the RGB+Depth data:
        getNextObservation(out_obs,there_is_obs, hardware_error);

        // If successful, fill out the accelerometer data:
        if (there_is_obs && this->m_grab_IMU)
        {
                double acc_x=0,acc_y=0,acc_z=0; // In m/s^2
                bool  has_good_acc=false;

#if MRPT_HAS_KINECT_FREENECT
                {
                        freenect_update_tilt_state(f_dev);
                        freenect_raw_tilt_state* state = freenect_get_tilt_state(f_dev);
                        if (state)
                        {
                                has_good_acc = true;
                                double lx,ly,lz;
                                freenect_get_mks_accel(state, &lx, &ly, &lz);

                                // Convert to a unified coordinate system:
                                // +x: forward
                                // +y: left
                                // +z: upward
                                acc_x = -lz;
                                acc_y = -lx;
                                acc_z = -ly;
                        }
                }
#endif

                // Common part for any implementation:
                if (has_good_acc)
                {
                        out_obs_imu.sensorLabel = out_obs.sensorLabel + "_IMU";
                        out_obs_imu.timestamp   = out_obs.timestamp;
                        out_obs_imu.sensorPose = out_obs.sensorPose;

                        for (size_t i=0;i<out_obs_imu.dataIsPresent.size();i++)
                                out_obs_imu.dataIsPresent[i] = false;

                        out_obs_imu.dataIsPresent[IMU_X_ACC] = true;
                        out_obs_imu.dataIsPresent[IMU_Y_ACC] = true;
                        out_obs_imu.dataIsPresent[IMU_Z_ACC] = true;

                        out_obs_imu.rawMeasurements[IMU_X_ACC] = acc_x;
                        out_obs_imu.rawMeasurements[IMU_Y_ACC] = acc_y;
                        out_obs_imu.rawMeasurements[IMU_Z_ACC] = acc_z;
                }
        }
}


/* -----------------------------------------------------
                                setPathForExternalImages
----------------------------------------------------- */
void CKinect::setPathForExternalImages( const std::string &directory )
{
        MRPT_UNUSED_PARAM(directory);
        // Ignore for now. It seems performance is better grabbing everything
        // to a single big file than creating hundreds of smaller files per second...
        return;

//      if (!mrpt::system::createDirectory( directory ))
//      {
//              THROW_EXCEPTION_FMT("Error: Cannot create the directory for externally saved images: %s",directory.c_str() )
//      }
//      m_path_for_external_images = directory;
}


/** Change tilt angle \note Sensor must be open first. */
void CKinect::setTiltAngleDegrees(double angle)
{
        ASSERTMSG_(isOpen(),"Sensor must be open first")

#if MRPT_HAS_KINECT_FREENECT
        freenect_set_tilt_degs(f_dev,angle);
#else
        MRPT_UNUSED_PARAM(angle);
#endif

}

double CKinect::getTiltAngleDegrees()
{
        ASSERTMSG_(isOpen(),"Sensor must be open first")

#if MRPT_KINECT_WITH_FREENECT
        freenect_update_tilt_state(f_dev);
        freenect_raw_tilt_state *ts=freenect_get_tilt_state(f_dev);
        return freenect_get_tilt_degs(ts);
#else
        return 0;
#endif
}